JP2007041122A - Method of manufacturing polymer optical waveguide, polymer optical waveguide, and optical module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily manufacture a polymer optical waveguide for bending a light beam transmitting through a core in a direction opposite to a substrate. <P>SOLUTION: In the method of manufacturing the polymer optical waveguide, which is provided with a core 13, a reflection surface 15 in which one end face of the core is formed into an overhanging slope to reflect a light beam transmitting through the core in the direction opposite to the substrate, and an over-clad 14 for covering the substrate including the core on a substrate 11, a sacrificial layer 21 having a slope 22 forming the reflection face 15 of the core 13 is formed on the substrate 11, a core material is formed in a part including at least the slope 22 of the sacrificial layer 21 on the substrate 11, the core 13 is formed by patterning the core material, the sacrificial layer 21 is removed to make one end face of the core 13 into the reflection surface 15, and the over-clad 14 covering the substrate 11 including the core 13 is formed on the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a polymer optical waveguide and a polymer optical waveguide, and more particularly to a method for manufacturing a polymer optical waveguide for bending and propagating an optical signal propagating in a core layer, a polymer optical waveguide, and an optical module using the same. It is about.

  In recent years, application of polymer optical waveguides to optical interconnection has been attempted. In optical interconnection, a polymer optical waveguide having an optical path conversion function that bends the optical path sharply (for example, in a direction perpendicular to the substrate) is formed, and optical components such as a light source and a detector are mounted on the surface of the polymer optical waveguide. An optical module is used.

  In general, methods for producing a polymer optical waveguide include a method using dry etching, a method using pattern exposure and development, and a method using a mold.

  As an optical path conversion unit for bending an optical path, there is a method of cutting a core with a dicing saw and forming the cut surface on a light reflecting surface.

  Further, there is a method in which after forming a core having a reflective surface with a concave mold, the core is transferred to a clad, and finally an over clad is provided around the core (see, for example, Patent Document 1).

  In addition, a recess is formed on the substrate, a polymer material (core material) is applied on the substrate to form a core, and after removing the core material other than the recess on the substrate, a clad is provided on the entire surface of the substrate, There is a method in which the core and the clad are transferred onto another substrate (see, for example, Patent Document 2).

  As a method of manufacturing a polymer optical waveguide in which a metal mirror is provided on the end face of the core as a reflection surface, a clad is formed flat, a metal layer to be a mirror is formed on the clad, and the metal layer is etched to have a slope. Thus, there is a method of forming a metal mirror (see, for example, Patent Document 3).

JP 2004-78084 A JP 2001-332870 A JP 2002-107561 A

  However, the conventional method for manufacturing a polymer optical waveguide provided with an optical path changing part has the following problems.

  (1) In a manufacturing method in which a core is cut using a dicing saw and the cut surface is formed as a reflecting surface, it is difficult to cut only a desired core in the optical waveguide. ) May be excavated or cut, and the strength and characteristics of the optical waveguide may be adversely affected.

  (2) In a manufacturing method in which a core having a reflective surface is separately formed and the core is provided on a substrate or a clad, the number of manufacturing steps is large and manufacturing time is required. As a result, it becomes a factor that increases the cost.

  Further, in order to form an optical circuit that bends light propagating through the core in the direction opposite to the substrate, the core having a reflective surface is formed using a mold, and the core is attached to the substrate for manufacturing. Is provided on the substrate via the adhesive layer, the presence of the adhesive layer affects the light propagating through the core, and optical characteristics such as loss are deteriorated.

  (3) In a polymer optical waveguide in which a metal mirror is provided on the end face of the core as a reflection surface, a metal layer is formed and then the metal layer is etched to form a reflection surface. It must be formed thick, and it takes time to stack and etch the metal layer.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a polymer optical waveguide manufacturing method, a polymer optical waveguide, and an optical waveguide capable of easily and quickly producing a polymer optical waveguide that bends light propagating in the core in the direction opposite to the substrate. To provide a module.

  In order to achieve the above object, the invention of claim 1 is characterized in that a core and one end face of the core are formed in an overhanging inclined surface to reflect light propagating in the core in a direction opposite to the board. In the method of manufacturing a polymer optical waveguide comprising a reflecting surface to be formed and an overcladding covering the substrate including the core, a sacrificial layer having an inclined surface for forming the reflecting surface of the core is formed on the substrate. The core material is formed on the substrate including at least the sacrificial layer including the inclined surface, the core material is patterned to form the core, and the sacrificial layer is removed to form one end surface of the core on the reflective surface. And a method of manufacturing a polymer optical waveguide in which an overcladding covering a substrate including a core is formed.

The invention of claim 2 includes a core, a reflection surface that reflects light propagating in the core in a direction opposite to the substrate by forming one end face of the core as an overhanging inclined surface on the substrate, and the core. In a method of manufacturing a polymer optical waveguide having an overclad covering a substrate,
A sacrificial layer having an inclined surface for forming a reflective surface of the core is formed on the substrate, a mold having a core shape is placed, and a core material is injected into the mold to at least sacrifice the substrate. A core is formed on a portion including an inclined surface of the layer, the sacrificial layer is removed, one end surface of the core is formed on a reflective surface, and an overcladding covering the core including the core is formed on the substrate. It is a manufacturing method of a polymer optical waveguide.

  According to a third aspect of the present invention, there is provided the method for producing a polymer optical waveguide according to the first or second aspect, wherein the exit window is formed by removing the over clad in the vicinity of the reflection surface of the core.

  According to a fourth aspect of the present invention, there is provided the polymer light guide according to any one of the first to third aspects, wherein the sacrificial layer is formed so that an angle between the inclined surface of the sacrificial layer and the surface of the sacrificial layer on the substrate side is approximately 45 °. It is a manufacturing method of a waveguide.

  In the invention of claim 5, an ultraviolet curable resin is used for the core material, and an ultraviolet curable resin layer is formed on a portion including at least the inclined surface of the sacrificial layer on the substrate, and then the ultraviolet curable resin layer is irradiated with ultraviolet rays. 5. The method for producing a polymer optical waveguide according to claim 1, wherein the core is formed and portions other than the core are removed with a developer.

  According to a sixth aspect of the present invention, the sacrificial layer is formed of a material soluble in the developer, and when the UV curable resin layer other than the core is removed by the developer, the sacrificial layer is used with the developer. 6. The method for producing a polymer optical waveguide according to claim 5, wherein the layer is also removed at the same time.

  The invention according to claim 7 is the method for producing a polymer optical waveguide according to any one of claims 1 to 6, wherein the sacrificial layer is formed using a thermoplastic resin as a material and a mold material.

  The invention of claim 8 is a polymer optical waveguide manufactured using the method for manufacturing a polymer optical waveguide according to any one of claims 1 to 7.

  A ninth aspect of the present invention is an optical module comprising the polymer optical waveguide according to the eighth aspect and a light source and / or a photodetector provided above the reflection surface of the polymer optical waveguide.

  According to the present invention, it is possible to easily produce a polymer optical waveguide that bends light propagating in the core in the direction opposite to the substrate.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a sectional view showing a preferred embodiment of a polymer optical waveguide according to the present invention.

  The polymer optical waveguide 10 of the present embodiment includes a substrate 11, an underclad 12 provided on the substrate 11, a core 13 provided on the underclad 12 and having a rectangular cross section, and an underclad 12 including the core 13. And an overcladding 14 formed so as to cover the surface. For example, the core 13 is formed to extend from one side of the substrate 11 to the center of the substrate 11.

  In the polymer optical waveguide 10, the end surface of the core 13 on the center side of the substrate is formed on the reflection surface 15. The reflection surface 15 is formed in an overhang shape at the center side end of the substrate 11. That is, the reflecting surface 15 is formed in a direction in which light propagating through the core is reflected in the direction opposite to the substrate (upper side in FIG. 1), or light incident from above the overclad 14 is reflected into the core.

  Furthermore, a groove 16 is formed as an exit window in the over clad 14 in the vicinity of the reflecting surface 15 of the core 13. Thus, the end surface of the core 13 on the center side of the substrate faces the air, and the interface between the core 11 and the air region is the reflecting surface 15. In other words, the upper side of the obliquely formed end surface is the core region, and the lower side of the end surface is air. The light reflecting surface 15 forms a plane of approximately 135 ° (θ in FIG. 1) with respect to the bottom surface of the core (the surface on the underclad 12 side).

  In the polymer optical waveguide 10 of the present embodiment, the underclad 12 is provided on the substrate 11 and the core 13 is provided on the underclad 12. However, the substrate is formed of a polymer material having a refractive index sufficiently smaller than that of the core 13. When 11 is used, the underclad 12 may be omitted.

  Next, a method for manufacturing a polymer optical waveguide will be described.

  First, as shown in FIG. 2A, an underclad 12 is formed on a substrate 11 almost flatly. Examples of the substrate 11 include a glass (quartz) substrate, a silicon substrate, a polyimide substrate, a fluorinated acrylic substrate, a fluorinated polyimide substrate, and a glass epoxy substrate. Examples of the material for forming the underclad 12 include acrylic, epoxy, polyimide, fluorinated acrylic, and fluorinated polyimide.

  As shown in FIG. 2B, a sacrificial layer 21 is provided on the underclad 12. The sacrificial layer 21 is a layer serving as a mold for forming the reflecting surface 15 on the core 13, and an inclined surface 22 is formed at the center of the substrate 11. The sacrificial layer 21 is formed in a shape that complements the air region below the light reflecting surface 15 in FIG. 1 and has a width that is equal to or greater than the core width of the core 13 to be formed later. The inclined surface 22 forms a plane of approximately 45 ° with respect to the bottom surface of the sacrificial layer 21 (surface on the underclad 12 side).

  The sacrificial layer 21 is formed of a thermoplastic resin that is soluble in an organic solvent or an alkaline developer. Specific examples include acrylic resins and polycarbonate.

  In the present embodiment, the sacrificial layer 21 is formed on the underclad 12 using a mold material. Specifically, a mold material having a desired shape is bonded and fixed on the underclad 12, a thermoplastic resin is injected into the mold material, the thermoplastic resin is solidified on the underclad 12, and the mold is removed. . When the mold material is bonded and fixed on the underclad 12, the mold material is aligned with the underclad 12 while looking under a microscope or the like.

  Next, a liquid ultraviolet curable resin (UV curable resin) as a core material is applied onto the underclad 12 and the inclined surface 22 by spin coating. After the resin is applied and dried, the core material is irradiated with ultraviolet rays in accordance with a desired core pattern. The core material only needs to be applied on at least the inclined surface 22, but may also be applied to the upper surface of the sacrificial layer 21.

  As shown in FIG.2 (c), after irradiating with an ultraviolet-ray, the board | substrate 11 containing a core material is immersed in a developing solution, and the uncured part of a core material is dissolved in a developing solution. Thereby, a core material is formed in the core 13 which has a desired pattern. When the core material is a positive type ultraviolet curable resin, the core material to be removed is irradiated (exposed) with ultraviolet rays, and the unirradiated portion is cured. When the core material is a negative ultraviolet photosensitive resin, the core material to be left as a pattern is irradiated with ultraviolet rays to cure the irradiated portion. Regardless of which ultraviolet curable resin is used, the cured portion becomes the core 13 and the core material other than the core 13 is removed.

  Here, in this embodiment, the core material is formed by using a direct exposure method in which the core material is exposed to ultraviolet light and cured, and an uncured portion of the core material is removed using a developer. However, the method for forming the core is not limited to this, and a mask having a pattern of the core 13 (for example, a resist mask or a metal mask) is formed on the core material, and the RIE (reactive ion etching) method is used. The core may be formed by etching. Alternatively, the core 13 may be formed by placing a mold having a desired core pattern on the underclad 12, injecting a resin into the mold, and curing the resin.

  As shown in FIG. 2D, the sacrificial layer 21 is removed. The sacrificial layer 21 is removed by being immersed in an organic solvent, an alkaline developer or the like. At this time, when the sacrificial layer 21 is formed of a thermoplastic resin, the substrate 11 including the sacrificial layer 21 may be warmed to remove the sacrificial layer 21 in a liquid state.

  In the present embodiment, after irradiating the core material with ultraviolet rays, the uncured portion of the core material and the sacrificial layer 21 are simultaneously removed using a developer in which both the core material and the sacrificial layer 21 are soluble. Specifically, by using a negative thermosetting resin for the core material, the portion of the core material irradiated with ultraviolet rays is cured. Here, the ultraviolet ray is irradiated to the portion below the inclined surface 22 of the sacrificial layer 21 by the ultraviolet ray irradiation to the core material, but the sacrificial layer 21 is different from the resin forming the core material. A resin that does not cure (does not react to ultraviolet rays) is used. Therefore, when the substrate 11 including the core material and the sacrificial layer 21 is immersed in the developer, all the sacrificial layers 21 including the lower portion of the inclined surface 22 and the uncured portion of the core material are dissolved in the developer. The end face of the core 13 can be formed in an overhang shape.

  As shown in FIG. 2E, an over clad 14 that covers the core 13 is provided on the core 13 and the under clad 12. The material for forming the overclad 14 is preferably an ultraviolet curable resin.

  After the overcladding 14 is formed, the overcladding 14 near the reflecting surface 15 is removed. Specifically, a photomask 23 that transmits ultraviolet light in the vicinity of the reflecting surface 15 and blocks ultraviolet light is disposed above the overcladding 14 and is blocked by the overcladding 14 via the photomask 23. Irradiate ultraviolet rays UV. In the present embodiment, a negative type ultraviolet curable resin is used as a material for forming the over clad 14, and a portion of the over clad 14 exposed to ultraviolet rays is a cured portion.

  As shown in FIG. 2 (f), after irradiating with ultraviolet rays, the overclad 14 is immersed in a developing solution to remove the uncured portion, and the groove 16 is formed. The end face of the core 13 is located in the groove 16 formed by partially removing the over clad 14, and the end face is in contact with air, so that a reflective surface 15 having high reflectivity is formed. The polymer optical waveguide 10 is obtained by the above process.

  In the present embodiment, the over clad 14 is formed of an ultraviolet curable resin, and the groove 16 is formed by the direct exposure method described above. In this direct exposure method, the uncured portion of the clad is removed with the developer, so that the developer sufficiently flows under the end surface (reflecting surface 15) of the core 13, and the over clad material below the core end surface is removed. The reflection surface 15 which can be removed and the end surface of the core 13 is in contact with the air layer can be formed.

  Further, as shown in FIG. 2G, a light source (for example, a laser diode (LD)) 25 or a light detection element (for example, a photodiode (PD)) is provided on the overcladding 14, and a polymer optical waveguide type is provided. The optical module 24 is obtained. The light source 25 is held on the groove 16 by the light source holding member 26 so as to be positioned immediately above the reflecting surface 15. The light source holding member 26 is bonded onto the over clad 14 with solder bumps 27. Furthermore, as shown in FIG. 3, a lens 31 for condensing light may be provided between the light source 25 and the reflecting surface 15.

  According to the method of manufacturing the polymer optical waveguide 10 of the present embodiment, the step of forming the sacrificial layer 21 and the step of removing the sacrificial layer 21 after forming the core 13 are added to the manufacturing process of the conventional polymer optical waveguide. Thus, a polymer optical waveguide having a structure in which light propagating through the core 13 is bent and transmitted in a direction perpendicular to the substrate 11 can be manufactured. That is, it is possible to easily produce a polymer optical waveguide that can bend the light propagating through the core 13 in a direction perpendicular to the substrate 11 without making a significant change by using a conventional polymer optical waveguide manufacturing process. it can.

  Here, unlike the polymer optical waveguide 10 of FIG. 1, a reflection film needs to be provided on the end surface of the core 13 in an optical waveguide that does not have the groove 16, that is, in an optical waveguide that does not contact the light reflecting surface 15. However, it is difficult to provide a metal film (for example, gold) on the end face of the core as a reflective film. This is because the thickness and width of the core are on the order of several μm, and it is difficult to deposit a metal film only on the end face of the core using the metal deposition method.

  Therefore, in the present embodiment, the end surface of the core 13 on the center side of the substrate 11 is formed so as to face the air, and the reflection surface with a high reflectivity at the end surface of the core 13 is used. It can be easily manufactured.

  Further, in FIG. 2D, a mold having a desired pattern shape is used separately from the undercladding 12, and the core formed by the mold is sharpened as shown in FIG. It is conceivable that it is formed by being attached to the under clad so that is on the upper side (the side opposite to the substrate 11 in FIG. 2).

  However, in order to affix the core formed of the mold on the substrate, an adhesive layer that adheres the core 13 to the under clad is required. It is difficult to control the thickness of the adhesive layer, and the adhesive layer having a non-uniform thickness affects the optical transmission characteristics of the core. In addition, the core 13 is formed with a fine pattern, and may be damaged when the core is stuck on the underclad. Further, the adhesive layer is generally more easily contracted than the ultraviolet curable resin forming the core and the clad, and the polymer optical waveguide is bent due to the contraction of the adhesive layer.

  Therefore, according to the method of manufacturing the polymer optical waveguide 10 of the present embodiment, after forming the sacrificial layer 21, the core material is formed by directly applying the ultraviolet curable resin onto the underclad 12 by spin coating or the like. Thus, it is possible to produce a polymer optical waveguide having no optical deflection and good optical transmission characteristics.

  In addition, the polymer optical waveguide 10 manufactured by the method for manufacturing a polymer optical waveguide according to the present embodiment does not have a step of attaching a core. Therefore, it is possible to reduce manufacturing errors caused by attaching a core having a fine pattern.

  In the method of manufacturing the polymer optical waveguide 10 of the present embodiment, after irradiating the core material with ultraviolet rays, an uncured portion of the core material and the sacrificial layer are formed using a developer in which both the core material and the sacrificial layer 21 are soluble. However, the sacrificial layer 21 may be removed after the pattern of the core 13 is formed.

  The sacrificial layer 21 may be removed after the overcladding 14 is formed. At this time, it is preferable to form a flow path in the over clad 14 for discharging the thermoplastic resin that has formed the sacrificial layer 21.

  In the present embodiment, the reflection surface 15 of the polymer optical waveguide 10 is formed in a planar shape, but may be formed in a curved surface shape. For example, if the end surface of the core 13 is formed in a convex shape so that the focal point of the reflecting surface 15 is the light source 25, the reflecting surface 15 can have a condensing function, and it is necessary to provide the lens 31 shown in FIG. Absent.

  Next, embodiments of the present invention will be described based on examples, but the embodiments of the present invention are not limited to these examples.

  Example 1 A UV curable acrylic material (refractive index of 1.51) was applied onto a glass epoxy substrate by spin coating, and the acrylic material was cured by irradiating with ultraviolet rays to form an underclad. Next, a sacrificial layer was formed by a mold method using a thermoplastic resin soluble in acetone. After the sacrificial layer was formed, a UV curable acrylic material (refractive index of 1.59) was applied as a core material by a spin coating method, and the core material was irradiated with UV through a mask having a pattern of the core to form a core. Thereafter, the uncured portion of the core material and the sacrificial layer were simultaneously removed using acetone as a developer.

  Next, the clad material was applied by a spin coat method, and the over clad was cured by irradiating the over clad with ultraviolet rays through a mask having a pattern in which grooves were formed in the over clad near the reflecting surface. Thereafter, the unexposed portion of the overclad material was removed using acetone as a developer to obtain a polymer optical waveguide. Finally, an LD or PD was provided above the reflection surface of the polymer optical waveguide to produce an optical module.

  Example 2 An optical module was fabricated in the same manner as in Example 1 except that a UV curable acrylic material having a refractive index of 1.44 was used as a material for forming the underclad.

  (Example 3) A UV curable acrylic material (refractive index of 1.51) was applied onto a glass epoxy substrate by spin coating, and the acrylic material was irradiated with ultraviolet rays and cured to form an underclad. Next, a sacrificial layer was formed by a mold method using a thermoplastic resin soluble in acetone. After forming the sacrificial layer, a mold having a core pattern is placed on the undercladding, an ultraviolet curable resin to be the core is injected into the mold, and the ultraviolet curable resin is cured with ultraviolet rays to form the core. did.

  Next, an overcladding was formed. The overclad was formed using a mold in which grooves and flow passages were formed in the overclad. Thereafter, the sacrificial layer was removed with acetone, and an LD or PD was provided on the overcladding to produce an optical module.

It is sectional drawing which shows suitable embodiment of the polymer optical waveguide which concerns on this invention. (A)-(f) is sectional drawing explaining the manufacturing method of the polymer optical waveguide of FIG. 1, (g) is sectional drawing which shows the optical module using the polymer optical waveguide of (f). It is sectional drawing which shows the modification of the optical module of FIG.2 (g).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polymer optical waveguide 11 Substrate 12 Under clad 13 Core 14 Over clad 15 Reflecting surface 21 Sacrificial layer 22 Inclined surface UV Ultraviolet

Claims (9)

On the substrate, a core, a reflective surface that reflects light propagating in the core in the opposite direction by forming one end surface of the core in an overhanging inclined surface, and an overcladding that covers the substrate including the core In a method for producing a polymer optical waveguide comprising:
A sacrificial layer having an inclined surface for forming a reflective surface of the core is formed on the substrate, a core material is formed on a portion including the inclined surface of at least the sacrificial layer on the substrate, and the core material is patterned. Forming a core, removing the sacrificial layer, forming one end surface of the core as a reflective surface, and forming an overcladding covering the core including the core on the substrate. . On the substrate, a core, a reflective surface that reflects light propagating in the core in the opposite direction by forming one end surface of the core in an overhanging inclined surface, and an overcladding that covers the substrate including the core In a method for producing a polymer optical waveguide comprising:
A sacrificial layer having an inclined surface for forming a reflective surface of the core is formed on the substrate, a mold having a core shape is placed, and a core material is injected into the mold to at least sacrifice the substrate. A core is formed on a portion including an inclined surface of the layer, the sacrificial layer is removed, one end surface of the core is formed on a reflective surface, and an overcladding covering the core including the core is formed on the substrate. A method for producing a polymer optical waveguide.   3. The method of manufacturing a polymer optical waveguide according to claim 1, wherein an exit window is formed by removing an over clad in the vicinity of the reflection surface of the core.   The method for producing a polymer optical waveguide according to claim 1, wherein the inclined surface of the sacrificial layer is formed at an angle of approximately 45 °.   An ultraviolet curable resin is used for the core material, and an ultraviolet curable resin layer is formed on at least a portion of the substrate including the inclined surface of the sacrificial layer, and then the ultraviolet curable resin layer is irradiated with ultraviolet rays to form the core. 5. The method for producing a polymer optical waveguide according to claim 1, wherein a portion other than the core is removed with a developer.   The sacrificial layer is formed of a material soluble in the developer, and when the ultraviolet curable resin layer other than the core is removed by the developer, the sacrificial layer is also removed simultaneously with the developer. 6. A method for producing a polymer optical waveguide according to 5.   The said sacrificial layer is a manufacturing method of the polymer optical waveguide in any one of Claims 1-6 made from a thermoplastic resin as a material and using a mold material.   A polymer optical waveguide manufactured using the method for manufacturing a polymer optical waveguide according to claim 1. An optical module comprising: the polymer optical waveguide according to claim 8; and a light source and / or a light detector provided above a reflection surface of the polymer optical waveguide.

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